/*
 * Copyright (c) JoinQuant Development Team
 * Author: Huayong Kuang <kuanghuayong@joinquant.com>
 */

#include <iostream>

using namespace std;



int main(void)
{
    string s = "Hello world!";

    cout << s << endl;
    cout << "at(0): " << s.at(0) << endl;
    cout << "front: " << s.front() << endl;
    cout << "back: " << s.back() << endl;
    cout << "data: " << s.data() << endl;

    return 0;
}

